Expandable medical device with tapered hinge

Abstract

According to the present invention there is provided an expandable medical device having, a plurality of elongated beams, the plurality of elongated beams joined together to form a substantially cylindrical device which is expandable from a cylinder having a first diameter to a cylinder having a second diameter. A plurality of hinges connecting the elongated beams have a hinge width, wherein the hinge width is smaller than the beam width. A pawl is disposed adjacent to and substantially parallel to the hinge prior to expansion of the medical device and a plurality of teeth are adapted to receive the pawl. The present invention additionally provides the benefit of limiting the amount of recoil of an expandable device by engaging a locking mechanism, thereby retaining the expanded diameter of the device.

1. An expandable medical device comprising:
 a plurality of elongated beams, the plurality of elongated beans joined together to form substantially cylindrical elements which are expandable from cylinders having a first diameter to cylinders having a second diameter, the plurality of elongated beams having a beam width in a circumferential direction and wherein adjacent elongated beams form substantially V-shapes when the cylinders are at the second diameter; 
 a plurality of flexible links interconnecting the substantially cylindrical elements; and 
 a plurality of hinges connecting the elongated beams and positioned away from apexes of the substantially V-shapes, wherein deformation during expansion is confined substantially to the hinges and the flexible links, wherein the plurality of hinges each have a tapered portion such that an end of each hinge closer to the apex of the substantially V-shapes formed by the adjacent elongated beams has a width which is greater than a width of the hinge at an opposite end, and the tapered portion has a length longer than a non-tapered portion of the hinge. 
 
     
     
       2. The device of  claim 1 , wherein the plurality of hinges taper substantially linearly. 
     
     
       3. The device of  claim 1 , wherein the non-tapered portion extends along about ⅓ of the length of the hinge and the tapered portion extends along about ⅔ of the length of the hinge. 
     
     
       4. The device of  claim 1 , wherein during expansion the hinges experience deformation below their elastic limit. 
     
     
       5. The device of  claim 1 , wherein during expansion a structure adjacent the hinges experiences at least two degrees of freedom of motion. 
     
     
       6. The device of  claim 1 , wherein the plurality of hinges are tapered with the hinge widths, hinge length, and taper adjusted to achieve a desired value of the maximum strain along the hinges. 
     
     
       7. The device of  claim 1 , wherein the taper is substantially constant along a length of about ⅔ of a length of the hinge. 
     
     
       8. The device of  claim 1 , wherein the taper extends along a length of about ⅔ of a length of the hinge. 
     
     
       9. The device of  claim 1 , comprising a pawl disposed adjacent to the hinge and a plurality of teeth adapted to receive the pawl in a locking configuration. 
     
     
       10. The device of  claim 9 , wherein during expansion, the pawl experiences at least two degrees of freedom of motion. 
     
     
       11. The device of  claim 1 , wherein the device is laser-cut. 
     
     
       12. The device of  claim 1 , wherein the elongated beams further include a plurality of apertures disposed therein and a beneficial agent disposed within the apertures. 
     
     
       13. The device of  claim 1 , wherein a recoil of the medical device after expansion to the second diameter is less than about eight percent. 
     
     
       14. The device of  claim 1 , wherein a recoil of the medical device after expansion to the second diameter is less than about five percent. 
     
     
       15. The device of  claim 1 , wherein the device is manufactured of a biodegradable material. 
     
     
       16. The device of  claim 1 , wherein the device is manufactured of Nitinol, polymer, or a composite of polymer and Nitinol. 
     
     
       17. An expandable medical device according to  claim 1 , wherein the width of the hinge closest to the apex of the substantially V-shapes is smaller than the beam width. 
     
     
       18. An expandable medical device according to  claim 1 , wherein the hinges are coaxial with an adjacent elongated beam when the stent is in the first diameter. 
     
     
       19. An expandable stent comprising:
 a plurality of elongated beams joined together to form a substantially cylindrical elements which are expandable from cylinders having a first diameter to cylinders having a second diameter, wherein adjacent ones of the plurality of elongated beams form substantially V-shapes when the cylinders are at the second diameter; 
 a plurality of flexible links interconnecting the substantially cylindrical elements; and 
 a plurality of hinges connecting the elongated beams and positioned away from apexes of the substantially V-shapes, wherein deformation during expansion is confined substantially to the hinges and the flexible links, wherein the plurality of hinges each includes a tapered portion such that an end of each hinge closer to the apex of the substantially V-shapes formed by the adjacent elongated beams has a width which is greater than a width of the hinge at an opposite end, and wherein substantially the entire tapered portion of the hinge deforms during expansion of the cylinder from the first diameter to the second diameter. 
 
     
     
       20. The stent of  claim 19 , wherein the tapered portion tapers substantially linearly. 
     
     
       21. The stent of  claim 19 , wherein a non-tapered portion of the hinge extends along about ⅓ of the length of the hinge and the tapered portion of the hinge extends along about ⅔ of the length of the hinge. 
     
     
       22. The stent of  claim 19 , wherein during expansion the hinges experience deformation below their elastic limit. 
     
     
       23. The stent of  claim 19 , wherein during expansion a structure adjacent the hinges experiences at least two degrees of freedom of motion. 
     
     
       24. The stent of  claim 19 , wherein the plurality of hinges are tapered with the hinge widths, hinge length, and taper adjusted to achieve a desired value of the maximum strain along the hinges. 
     
     
       25. The stent of  claim 19 , wherein the taper is substantially constant along a length of about ⅔ of a length of the hinge. 
     
     
       26. The stent of  claim 19 , wherein the taper extends along a length of about ⅔ of a length of the hinge. 
     
     
       27. The stent of  claim 19 , comprising a pawl disposed adjacent to the hinge and a plurality of teeth adapted to receive the pawi in a locking configuration. 
     
     
       28. The stent of  claim 27 , wherein during expansion, the pawl experiences at least two degrees of freedom of motion. 
     
     
       29. The stent of  claim 19 , wherein the device is laser-cut. 
     
     
       30. The stent of  claim 19 , wherein the elongated beams further include a plurality of apertures disposed therein and a beneficial agent disposed within the apertures. 
     
     
       31. The stent of  claim 19 , wherein a recoil of the medical device after expansion to the second diameter is less than about eight percent. 
     
     
       32. The stent of  claim 19 , wherein a recoil of the medical device after expansion to the second diameter is less than about five percent. 
     
     
       33. The stent of  claim 19 , wherein the device is manufactured of a biodegradable material. 
     
     
       34. The stent of  claim 19 , wherein the device is manufactured of Nitinol, polymer, or a composite of polymer and Nitinol. 
     
     
       35. The stent of  claim 19 , wherein the width of the hinge closest to the apex of the substantially V-shapes is smaller than the beam width. 
     
     
       36. The stent of  claim 19 , wherein the hinges are axially aligned with an adjacent elongated beam when the stent is in the first diameter.